Vitamin D

Question 1

What are the factors affecting Vit D synthesis

Answer 1

Melanin, UVB, Age, UVB shielding

Question 2

Where does Vit D synthesis begin

Answer 2

The skin

Question 3

What “pushes start button” in Vit D synthesis

Answer 3

The sun

Question 4

What molecule begins Vit D synthesis in skin

Answer 4

Cholesterol

Question 5

Acetyl CoA and Cholesterol create which form of Vit D in the skin

Answer 5

proVitD3 - 7-Dehydrocholesterol

Question 6

ProVitD3 + UVB =

Answer 6

PreVitD3

Question 7

PreVitD3 + Skin Temp =

Answer 7

Vitamin D3

Question 8

What is the animal source of VitD3

Answer 8

Cholecalciferol

Question 9

What is the plant source of Vitamin D

Answer 9

Ergocalciferol - VitD2

Question 10

Why is VitD2 “not as good” as VitD3

Answer 10

Does not stay in the blood as long

Question 11

VitD3–>Circulation–>Liver–>25-OHase =

Answer 11

25(OH)D3

Question 12

What enzyme converts VitD3 to 25(OH)D3?

Answer 12

25-OHase

Question 13

What converts ProVitD3 to PreVitD3

Answer 13

UVB

Question 14

What is another name for ProVitD3

Answer 14

7-Dehydrocholesterol

Question 15

What converts PreVitD3 to Vitamin D3

Answer 15

Skin temperature

Question 16

25(OH)D3 –>1-OHase in kidney =

Answer 16

1,25(OH)2D3 - Calcitriol

Question 17

What is the active form of Vitamin D

Answer 17

Calcitriol - 1,25(OH)2D3

Question 18

What enzyme converts 25(OH)D3 to Calcitriol

Answer 18

1-OHase

Question 19

Where does 1-OHase convert 25(OH)D3 to Calcitriol

Answer 19

Kidneys

Question 20

How is Vitamin D status measured (form)

Answer 20

25(OH)D3

Question 21

When is it best to measure Vitamin D status

Answer 21

End of winter (storage in adipose used up)

Question 22

Where is Vitamin D stored

Answer 22

Adipose tissue

Question 23

When will Vitamin D status be highest

Answer 23

August/September

Question 24

What can cause Vitamin D deficiency (organs)

Answer 24

Liver/kidney failure

Question 25

What is a treatment for Vitamin D deficiency (organ failure)

Answer 25

Calcitriol Rx (active form)

Question 26

What is a function of calcitriol in the kidneys

Answer 26

Increase calcium resorption (less excreted)

Question 27

Why don’t VitD and Calcium need to be taken at the same time

Answer 27

VitD still has to be activated, first to Calcitriol, then process to form Calbindin protein

Question 28

How is VitD absorbed

Answer 28

Follows the route of lipids

Question 29

How is VitD excreted

Answer 29

> 70% feces, urine

Question 30

What is the UL for VitD

Answer 30

4,000IU

Question 31

What is caused by VitD deficiency in children

Answer 31

Rickets

Question 32

What is caused by VitD deficiency in adults

Answer 32

Osteomalacia

Question 33

What are the symptoms of rickets

Answer 33

Bones don’t mineralize, bone still trying to grow, legs show symptoms because support body weight, growth retardation

Question 34

What are the symptoms of Osteomalacia

Answer 34

Poor bone mineralization; bones translucent

Question 35

What are food sources of VitD

Answer 35

Egg yolk, beef, tuna cheese, mushrooms, tofu, fortified milk

Question 36

What is the RDA for VitD 1-70years

Answer 36

600IU

Question 37

What is the RDA for VitD 70+years

Answer 37

800IU

Question 38

What is the Natl Osteoporosis Found recommendation for VitD 50+years

Answer 38

800-1000IU

Question 39

Why does sun over-exposure not result in VitD toxicity

Answer 39

too much UVB will destroy preVitD3

Question 40

What is VitD (Calcitriol) “claim to fame”

Answer 40

Calcium Homeostasis: Calcium absorption in enterocyte; Calcium resorption in kidney; Calcitriol, 24R,25(OH)2D3 & bone

Question 41

What are functions of VitD other than Calcium homeostasis

Answer 41

Cell differentiation, proliferation and growth-May prevent abnormal cell growth(cancer); Blood pressure, insulin secretion, autoimmune disorders; Blood volume control

Question 42

What is a symptom of VitD deficiency in children other than Rickets

Answer 42

Seizures